Significance of zircon trace element geochemistry,the Shihu gold deposit,western Hebei Province,North China
CAO Ye,LI Shengrong,ZHANG Huafeng,LIU Xiaobin,LI Zhenzhen,AO Chong,YAO Meijuan(1.State key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Beijing 100083,China;2.School of Earth Science and Resources,China University of Geosciences,Beijing 100083,China;3.Department of Earth Sciences,Laurentian University,Sudbury,P3E2C6,Canada)
The Shihu gold deposit is characterized by gold-bearing quartz-polymetallic sulfides and quartz veins.Both Mapeng granitoids batholith and intermediate-basic dikes intruded the metamorphic basement rocks,and are spatially associated with gold mineralization.Trace element abundances in zircons from the Shihu gold deposit,determined by laser-ablation microprobe ICPMS analysis,are sensitive to source rock type and crystallization environment.Concentrations of 21 trace elements were determined for zircons from granitoid rocks,diorites,quartz diorite porphyrites and gold-bearing quartz veins revealed some elemental characteristics and chondrite-normalized trace element patterns from different samples.There were no distinctive differences in REE concentrations of zircons from plutonic rocks and quartz veins,indicating that they probably had the same origin.Relatively flat chondrite-normalized REE patterns with(Yb/Sm)N ratios less than 60 characterized zircons from quartz diorite porphyrites and quartz veins.The highest Nb/Ta ratios were found in zircons from quartz diorite porphyrites,whereas the lowest ratios were found in quartz vein zircons.The Nb/Ta ratios were broadly correlated with HREE+Y contents,and had weak positive correlations with the depth of the Eu negative anomalies.High values U up to 0.4% and Th up to 0.1%,as well as positive correlations with REE+Y characterized zircons from quartz vein.The lowest Th/U ratios of zircons present in quartz veins reflected the relatively high concentration of U in hydrothermal fluid,and high Pb concentrations only typified quartz vein grains relatively enriched in U and Th.Zircons from quartz diorite porphyrites showed the most pronounced Ce anomalies,whereas weak Ce anomalies were typical of zircons from quartz veins,in which Eu/Eu* of zircons had a broadly negative correlation with Ce/Ce*.Trace element geochemistry of zircons from mineralized quartz veins and plutonic rocks confirmed that the sources of ore-forming materials were from Precambrian host rocks.Our results significantly enhanced the usefulness of zircon in crustal studies of the North China craton and as an indicator mineral in mineral exploration of the Taihang region.
【Fund】： supported by the National Natural Science Foundation of China(90914002);; the 111 Project under the Ministry of Education China(B07011)
【CateGory Index】： F426.32
【CateGory Index】： F426.32